Disclosed herein is an apparatus and method that detects the position of media in a media path.
Presently, devices such as printers, scanners, copiers, multi-function devices, and other devices interact with media, such as sheets, paper, transparencies, plastic, cardboard, or other media. In order for such devices to interact properly with the media, a device must be able to accurately detect the position of the media at various locations in a media path of the device. Media sensors can be used to detect media in the media path. The media sensors can be used for registration, such as position detection, for learning algorithms, for sheet size detection, and for other media sensing functions in a media path. The media path of a device can have baffles that provide enough space between them to accommodate various types of media and to efficiently transport the media. This space between the baffles can allow some variability for the fly height of media and can also allow some curling of media traveling through the media path.
Media sensors in a device can use a conical shaped beam of light reflected off of a reflector to detect the media location. The cone shaped beam of light can cause the light that is reflected off the reflector to also be conical shaped. Unfortunately, the variability of the fly height of media in the media path combined with the cone shaped light can cause a media sensor to start detecting media at different times, which can result in errors in the detected location of the media. For example, the variability of the fly height can result in errors when detecting the lead edge and the trail edge of media traveling through the media path.
For example, the baffles of a media path can be located 3 mm apart. This distance can allow for a variability of 3 mm in media fly height and/or curling of the media in the media path. This difference in media fly height and curling can cause a standard media sensor to have a location detection error of from 0.1 to 0.2 mm. Such an error is not acceptable for precise detection of media in a media path. Thus, there is a need for an apparatus and method that more accurately detects the position of media in a media path.